1945 Theatre Catalog, 4th Edition, Page 517

Another notable advance in the rapidly expanding science of air sanitation
is the adaptation of the Hygeaire system
for the radiant disinfection of air in
the theatre auditorium. This new development represents the first post-war application of the Hygeaire ultraviolet
germicidal unit (manufactured by the
American Sterilizer Company) for the
improvement in environmental sanitation
and for the practical control of airborne infection in the public health field.

Ever since the commercial development some four years ago of the hotcathode ultraviolet germicidal lamp, there
has been a keen interest and a highly
competitive effort among fixture manufacturers in an attempt to devise a practical means for the installation of the
ultraviolet lamp within the theatre auditorium. During the war years, a premium on engineering time and skill prevented a careful study of the various factors involved in such installations, although some very definite contributions
were made by certain scientific investigators in air-pollution surveys of both
air-conditioned and noneair-conditioned
theatres. As the result of insufiicient
technical data and information, progress in this field has been rather limited
and in recent months additional complications have developed, due to a diversity
of opinion as to the most efficient method
for the disinfection of air Within the
theatre auditorium.

FIGURE I.-De:ontaminatian and disinfection ettectiveness of air changes and
From an inspection of the
curves, it would appear that from 60 to 120 air changes an hour would have to be
maintained in order to have, of itself, any value in the prevention of the spread

air-change equivalents (lethes) an hour are shown.

By JOHN J. PERKINS

Issoriate Director of Research. American
Sterilizer Company

It is the duty of every theatre owner,
manager, or operator to familiarize himself with the present concept of sanitary
ventilation, its meaning, purpose and
ultimate effects upon the health and wellbeing of his patrons. Two schools of
thought, and two entirely different methods of approach to the problem of disinfecting the air within the theatre, are
being promoted at the present time.
Both of these methods are fairly simple
in principle and each has 'its recognized
advantages and disadvantages, even
though the end result in either case is the destruction of air-borne bacteria,
thereby assisting in the control of airborne infections in enclosed spaces.

The first and possibly the most widely .

publicized of these two methods applicable to the theatre field is the installation of ultraviolet germicidal lamps directly within the air-conditioning system, sometimes referred to as a duct installation. In contrast to the duct type
of installation is the method of direct
irradiation of the air in the upper areas
of the room in which the effects of sanitary ventilation are to be secured. This
method is now recognized to be a simple
and efficient method for the germicidal
treatment of air.

VENTILATION AND INFECTION

When individual and adequate supplies
of air can be furnished to each person,
the problem of air-borne infections disappears. However, it is almost impossible to arrive at such an ideal under
general living conditions, and it now becomes necessary for the purpose of this
discussion to determine just how much
can be done by ventilating procedures to
limit the spread of air-borne infection.
Almost everyone now recognizes that in
sneezing, coughing, spitting, breathing,
and speaking, bacteria and viruses are
projected into space. These agents are
disseminated in droplets of diverse sizes.
Droplets larger than 0.1 millimeter in
diameter will respond more rapidly to
gravitational force and will settle out a
short distance from their point of origin.
Eventually such droplets will dry and become part of the dust. The future of the
organisms they contain will depend on the steps taken to render this dust harmless. The behavior of dr0p1ets of smaller
size is somewhat diii'erent and the buoyancy of the atmosphere helps to maintain them in a state of suspension for
long intervals, and air currents may
transport them for long distances. When
these smaller droplets of less than 0.1
millimeter in diameter evaporate they
leave behind a residue of fine dust like
particles in which disease producing
germs may be incorporated.

of respiratory diseases by air-borne bacteria and viruses. Air conditioning systems
of such capacities are hardly feasible either in economy of operation or efficiency
or performance. (Permission to use this chart has been granted by Dr. L. J. Buttolph, of the General Electric Company's Lamp Department, Neia Park, Cleveland).

I073 #### -# I00
90 A so
so so
70 [A 70

DECONTAMINATION AND DISINFECTION EFFECTIVENESS or AIR
CHANGES AND AIR gHANGE EQUIVALENTS (LETHEs) PER HOUR